fix True/False/None reST markup

Doc/reference/datamodel.rst

 
 .. _datamodel:
 
 **********
 Data model
 **********
 
 
 .. _objects:
 
@@ skipping 1268 matching lines @@
    definition. Doing so means that not only will instances of the class raise an
    appropriate :exc:`TypeError` when a program attempts to retrieve their hash
    value, but they will also be correctly identified as unhashable when checking
    ``isinstance(obj, collections.Hashable)`` (unlike classes which define their
    own :meth:`__hash__` to explicitly raise :exc:`TypeError`).
 
    If a class that overrides :meth:`__eq__` needs to retain the implementation
    of :meth:`__hash__` from a parent class, the interpreter must be told this
    explicitly by setting ``__hash__ = <ParentClass>.__hash__``. Otherwise the
    inheritance of :meth:`__hash__` will be blocked, just as if :attr:`__hash__`
-   had been explicitly set to :const:`None`.
+   had been explicitly set to ``None``.
 
 
    .. note::
 
       By default, the :meth:`__hash__` values of str, bytes and datetime
       objects are "salted" with an unpredictable random value.  Although they
       remain constant within an individual Python process, they are not
       predictable between repeated invocations of Python.
 
       This is intended to provide protection against a denial-of-service caused
@@ skipping 765 matching lines @@
 
    Enter the runtime context related to this object. The :keyword:`with` statement
    will bind this method's return value to the target(s) specified in the
    :keyword:`as` clause of the statement, if any.
 
 
 .. method:: object.__exit__(self, exc_type, exc_value, traceback)
 
    Exit the runtime context related to this object. The parameters describe the
    exception that caused the context to be exited. If the context was exited
-   without an exception, all three arguments will be :const:`None`.
+   without an exception, all three arguments will be ``None``.
 
    If an exception is supplied, and the method wishes to suppress the exception
    (i.e., prevent it from being propagated), it should return a true value.
    Otherwise, the exception will be processed normally upon exit from this method.
 
    Note that :meth:`__exit__` methods should not reraise the passed-in exception;
    this is the caller's responsibility.
 
 
 .. seealso::
@@ skipping 80 matching lines @@
 
 .. rubric:: Footnotes
 
 .. [#] It *is* possible in some cases to change an object's type, under certain
    controlled conditions. It generally isn't a good idea though, since it can
    lead to some very strange behaviour if it is handled incorrectly.
 
 .. [#] For operands of the same type, it is assumed that if the non-reflected method
    (such as :meth:`__add__`) fails the operation is not supported, which is why the
    reflected method is not called.